FD Magnetic Resonance

Force detected magnetic resonance uses mechanical resonators (typically atomic force microscopy cantilevers) to detect magnetic resonance by measuring the forces on a magnetic probe due to spins in the sample of interest. Rather than measuring the resonance in a bulk sample as in conventional magnetic resonance, FDMR measures only the small region interacting with the probe, and thus forms the basis of Magnetic Resonance Force Microscopy (MRFM), first proposed by Sidles in 1991. The first FDMR measurements (by Rugar and co-workers in 1992) were ESR based, but the technique has been applied to NMR as well. The sensitivity achieved in some experiments is remarkable, with Rugar reporting single spin sensitivity in 2004.

Our approach to FDMR/MRFM employs higher fields than typical experiments in this field. High fields offer greater sensitivity and the smaller resonators that result from higher frequencies (94GHz in our case) will be easier to integrate with scanning probe systems. We have so far produced convincing results in fixed experiments with an estimated sensity of the order of 10^9 spins using commercial AFM cantilevers.